I am wondering what conclusions can be drawn from this sonar image.
The object is sunk in a river, of unknown age, and not examined.
Width 5,5 m Length 15,6 m Depth 9,7-9,2 m
The image was taken on a survey by this boat.
Apparently the river bottom is generally very hard clay—though not sure about this particular location.
Is it a boat as the link says? Could it be a bronze gun barrel from 500 years ago?
The gun Skiegge, big enough "for a cobbler to sit in its mouth", went through the ice while being transported across the river somewhere around that area in the 15th century. It's possible that Skiegge was bigger than any bronze gun that still exists. Also, I don't think we know the exact size and weight either.